Kahn still goes to work every day, keeping tabs on the financial firm he built with his family. His sister named Happy, lived to be 109. His baby brother Peter is a 105. Tom, Irving's son, is 69.

"We think it's normal!" explained Tom Kahn. "All of you journalists and other people are coming and saying this is amazing. We've always lived with it so it doesn't appear to us to be so extraordinary."

But it is. The Kahns are part of a group of Ashkenazi Jews, those from Eastern Europe, who live unusually long, healthy lives.

Irma Daniel, 104. and Lilly Port, 98, caught the attention of researchers who dubbed them 'super agers.' Dr. Nir Barzilai at the Albert Einstein College of Medicine has been studying them.

"We are trying to find out, what are those biological components that make us age at different rates?" said Barzilai.

Healthy lifestyle is not the key to the exceptional longevity seen among super agers. Sixty percent of the men, including Irving Kahn, smoked at some point. Less than half exercise on a regular basis and they don't eat particularly healthy diets.

Irving Kahn said his favorite food is "a rare hamburger...and a good cheese."

Barzilai and his team discovered that people who live to be 100 are more than twice as likely to have a certain variant of a gene called CETP. It helps control cholesterol and protects against heart disease and dementia. Irving Kahn has that gene variant.

According to Barzilai, 10 percent of people have the beneficial variant, whereas 20 to 24 percent of centenarians have it.

Barzilai says the future lies in developing drugs that could give everyone what super agers have naturally.

"Then we can really prevent all the age-related diseases that are making life so miserable for the elderly" said Barzilai.

Asked what he wanted his legacy to be, Irving Kahn said: "Worth knowing, worth being associated with. Not a bad fellow. If I borrowed money, I paid it back."

If he helps scientists find the keys to a longer life, Irving Kahn's legacy will be even richer.